The Australia batter has agreed to a three-match spell at Hove, taking in the County Championship matches against Worcestershire, Leicestershire and Glamorgan in May
Australia batter Steve Smith will tune up for this summer's Ashes series against England with a stint at Sussex.
The 33-year-old has signed up for three County Championship matches in May against Worcestershire, Leicestershire and Glamorgan.
Smith's spell comes ahead of the latest battle between the oldest rivals in international cricket, which begins on June 16 at Edgbaston.
It may also act as preparation for the World Test Championship final scheduled for the Kia Oval earlier in the month which Pat Cummins' Ashes holders are likely to be involved in.
"I am excited about joining Sussex for a few games in May and hopefully making a contribution to a successful season," Smith, who has scored 8,647 runs in 92 Tests for Australia, said.
Smith averaged 110.94 during Australia's last Ashes series in England (Ryan Pierse/Getty Images)
"I am particularly looking forward to working with the younger players in the squad and hoping I can provide some guidance to them."
The spell starts at New Road on May 4, where he spent a brief period during the 2010 T20 Blast season, before moving onto Grace Road on May 11.
Arguably the stand-out match comes in his only scheduled appearance at Hove for the visit of Marnus Labuschagne's Glamorgan on May 18.
Asked about the prospect of Smith arriving for a spell, England Test captain Ben Stokes said: "It's one of those where you probably prefer them not to get any game time in England before the Ashes."
Steve Smith's Australia Test batting recordTests: 92; Innings: 162; Runs: 8,647Highest score: 239; Average: 60.89; Strike rate: 54.38100s: 30; 50s: 37
Smith holds a formidable record in England. In 16 Tests he averages 59.55 - a figure that climbed to 110.94 during the 2019 Ashes.
This summer saw him move above Michael Clarke as Australia's fourth-highest Test run-scorer - thanks to his 30th century in the third South Africa Test - with 8,647 at an average of 60.89, which is only second to Don Bradman's 99.94.
Undoubtedly a fillip for the county game at a challenging time, it will see Smith paired with India's Chesteshwar Pujara who scored 1,094 runs in just eight County Championship appearances last summer.
Smith is back for a county spell for the first time since 2010 (Stu Forster/Getty Images)
Sussex chief executive Rob Andrew added: "To have arguably the world's best batter play for Sussex just before an eagerly awaited Ashes Test series is great for us and the County Championship.
"Our Championship form has not been good enough for a number of years, and under the new direction of head coach Paul Farbrace, we are looking to be positive and ambitious.
"Being able to attract a player of Steve Smith’s calibre is a massive statement and will be of great benefit to our young homegrown players, particularly our crop of talented young batters."
Elsewhere, Sussex are continuing their search for an overseas bowler for the new season after Jayden Seales was forced to withdraw from his deal due to a long-term knee injury.